Chlorinated hydrocarbon compositions



United States Patent W 40,491 US. Cl. 260-6525 2 Claims Int. Cl. C07c 21/04, 21/10, 21/12 ABSTRACT OF THE DISCLOSURE Stable chlorinatedhydrocarbon compositions are prepared by adding to the chlorinatedhydrocarbon an amine of the general formula H NANH where A is a bivalentaliphatic alkyl radical with 23 C atoms, together with pyrrole orN-methyl-pyrrole.

This invention relates to stabilizing chlorinated hydrocarbons and ithas for its object to provide a novel and improved process for thispurpose.

Another object of the invention is to enable chlorinated hydrocarbons tobe effectively stabilized by the addition thereto of very smallquantities of specific compounds hereinafter described.

Numerous solvents are used for degreasing metals, for dry cleaning andfor extraction purposes. Among these the unsaturated chlorinatedaliphatic hydrocarbons are preferred because of their high solventeffect and their incombustibility, especially, for instance,trichlorethylene. However, the advantage of their strong solvent effectis offset by the drawback of their poor stability which makes their usewithout prior stabilization very ditficult.

The decomposition of trichlorethylene, for instance, is caused by lightand oxygen and is catalyzed by heat and contact with metals. Thereforesmall quantities of additives are used to stabilize thetrichloroethylene or to neutralize the hydrogen chloride formed duringdecomposition. Particularly valuable additives are acid-bindingsubstances, like the basic amines which are customarily used to keeptrichlorethylene under alkaline conditions.

In order to retard oxidation it has also been suggested to use smallquantities of alcohols, phenols, N-alkyl pyrroles or epoxy compounds.

It is also known that the simultaneous addition of an alcohol and ofcertain amines gives the chlorinated hydrocarbons good stability againstdaylight.

We have now discovered that chlorinated hydrocarbons can be stabilizedeffectively by adding diamines, triamines or polyamines of the generalformula \NA (-I|-A u R2 \R to the chlorinated hydrocarbon either singlyor in mixtures. The letters in this formula represent:

R =R =R =R =R =H aliphatic alkyl radical with 1-3 carbon atoms, hydroxyalkyl radical with 1-3 carbon atoms or hydrogenated heterocyclic radicalwith 4-5 carbon atoms; A=bivalent 3,424,805 Patented Jan. 28, 1969aliphatic unsaturated alkyl radical with 2-3 carbon atoms or phenyleneradical; x=14; and n=04.

The addition of 0.001-002 weight percent of these compounds (referred tothe chlorinated hydrocarbon) to the chlorinated hydrocarbon to bestabilized, e.g. dichlorethylene, trichlorethylene, perchlorethylene,increases their resistance against iron and aluminum.

By using diamines, e.g. ethylene diamine, trimethylene diamine,triethylene diamine, l,2-di-(N,Nmorpholine-) ethane,1,2-di-(N,N-piperidine-) ethane, or triamines, e.g. diethylene triamine,or polyamines, e.g. tetraethylene pentamine, it is possible to obtain anexcellent stabilizing eflect. This can be increased by the addition ofaliphatic monoamines, e.g. diisopropyl amine or pyrrole orN-alkylpyrrols, e.g., N-methyl pyrrole. It has been found that evenquantities of 0002-0005 weight percent, referred to the chlorinatedhydrocarbon, have a surprising elfect.

The tabulated results of the stabilizing eifects show clearly the highdegree of stabilization achieved by our invention. The stabilizingeffect of various diamines, triamines and polyamines which are used toimprove the resistance of, for instance, trichlorethylene againstdecomposition by light and oxygen, is proven by the acceleratedoxidation test as per MIL-T4003 or Federal Specification 0T-634/ a,which is carried out as follows:

200 ml. of the trichlorethylene sample are placed in a retort. A steelstrip measuring /2 x 2" x $4 is hung up with a copper wire in the refluxcondenser and another steel strip measuring /4" x x ,4 is placed on thebottom of the retort. The input pipe for the water-saturated oxygen mustreach down to within A" from the bottom of the retort. The diameter andimmersion depth of the pipe below the water surface for controlling thepressure of the oxygen are fixed in such a manner that a stream ofoxygen of about 10-12 bubbles per minute, measured by a bubble counter,is produced. The heat source is a frosted lamp of watts which is mountedunderneath the retort. After 48 hours of reflux a sample is drawn, it isallowed to cool to room temperature and the acidity of the sample isthen determined in an aqueous extract by titration with 0.1 N NaOHagainst phenolphthalein as the indicator. After a 48 hour test theacidity must not exceed the value of 0.02 weight percent HCl, referredto trichlorethylene.

Example 1 4 samples of 200 m1. trichlorethylene which is stabilized with0.004 weight percent ethylene diamine are refluxed in a water-saturatedoxygen stream, a frosted lamp of 150 watts serving as the heat source.Small steel plates are mounted in the liquid and in the vapor phase. Asample is drawn after 48 hours and, after the sample has cooled, theacid components are extracted with 25 ml. water. The aqueous extract isthen titrated with 0.1 N NaOH against phenolphthalein as an indicator todetermine the acidity of the sample. After a 48 hour test treatment thesample is still alkaline. The heating is stopped when the acidity hasexceeded the limit of 0.02 Weight percent HCl, referred totrichlorethylene. In the case of 4 samples 0.020, 0.017, 0.021 and 0.019weight percent HCl were titrimetrically determined after 240 hours ofrefluxing, or an average of 0.019 weight percent HCl. Thus after 240hours of refluxing the acidity limit is not yet exceeded.

TABLE 1 Acidity Duration Acidity Test. N Additive (mg/kg.triehlorethylene) (percent HCl) (hours) (percent after 48 hrs. HO

1 0. 024 48 0. 089 96 0. 044 188 0. 055 240 0. 019 480 0. 011Triethylenediamine (200) 336 0. 014 8 Trimethylenediamine (200) 5040.011 9 1,2-propylenediamine (200) 456 0. 011 0 N,N'-triethylethylenediamine (200) 240 0.022 1N,N,NN-tetramethylcthylenediamine (200) 312 0.013 12N,Ndimethylethylenediamine (200) 528 0.015 13 Diethylenetriamine(200)..." 216 0. 020 4.- Tetraethylenepentamine (200) 144 0.015 151,2,4-trimethylpiperazine (200) 336 0.004 16.- N-oxethylpiperazine (200)Under 0.001... 264 0.010 17 1,2-di-(N,N-morpholine) ethane (200). "do168 0. 019

The results of tests 5, 6, 7, 8 and 9 show the considerably strongerinhibiting effect of a diamine over that of a monoamine (tests 2, 3, 4).The table also shows that ethylene diamine (tests 5, 6) and trimethylenediamine (test 8), i.e. the simple aliphatic non-substituted diamineshave the best effect.

Example 2 In a test made in accordance with Example 1, 200 ml.trichlorethylene with an additive of 0.004 weight percentdiisopropylamine and 0.004 weight percent ethylene diamine are refluxedfor 48 hours. After that period, and even after 450 hours heating thetest is still alkaline.

Example 3 We proceed as in Example 1, using small iron plates, whereeach time 20 ml. trichlorethylene are used to which stabilizing mixturesare added. The trichlorethylene which has been prepared in such a manneris then treated for several hours under reflux in a water-saturatedoxygen stream. Table 2 shows the results of these tests.

TABLE 2 Acidity Test Additive (mg.[k (Percent Duration Acidity No.trichlorothylene Hgl) (hours) (pfirccgnipt a or 48 hrs.

1 .{Di-isopropylamine (40) {Alkaline 192 0. 019

Ethylenediamine 2 .{Di-isopropylamine (40). .do 450 Ethylenediamine(40). 3 .{Di-isopropylamine (30) 0.015 62 0. 080

N -methylpyrrole (50)- 4 .-{Dl-isopropylamine (30).-.. 0.005 168 0.023

N-methylpyrrole (80) 5 --{Ethylenediamine (30)- {Alkaline. 432 0. 001

N-methylpyrrole (50). 6 .{Ethylenediamine (30).- ..do 816 0.010

N-methylpyrrole (80).- 7 {Di-isopropy1am1ne (30).-..{0 003 264 0. 029

N -methylpyrrole (100) 8 .-{Ethylenediamine (30)- {A1k81l118- 830 0. 023

N -metl1ylpyrrole (100) Di-isopropylamine (30) 9 Ethylenedlamine (10)--do 508 0. 017

N-rnethylpyrrole (100) 10 Di'isoprogoylamtne (3 96 0.038

yrro e 11 .{Ethylenediamine (30). .{Alkaline. 312 0. 009

Pyrrole (50) l Alkaline.

The test results shown in Table 2 demonstrate the synergism of thecombinations ethylene diamine/N- methyl pyrrole and pyrrole anddi-isopropylarnine/ethylene diamine. The table shows that the effect ofthe addition of 0.003 weight percent ethylene diamine and 0.01 weightpercent N-methyl pyrrole to trichlorethylene during the oxidation testresults in a resistance of trichlorethylene of more than 800 hours.Furthermore, the combination of di-isopropylamine/N-methyl pyrrole showsan acidity content of 0.08% I-ICl after 52 hours heating, while for thecombination ethylene diamine/N-methyl pyrrole after 432 hours an acidityof only 0.001% HCl is found.

The invention claimed is:

1. A chlorinated hydrocarbon selected from the group consisting ofdichlorethylene, trichlorclhylene and perchlorethylene containing from0.001 to 0.02 weight percent, related to said chlorinated hydrocarbon,of an amine selected from the group consisting of ethylene diamine,trimethylene diamine and 1,2-propy1ene diamine, and 0.005 to 0.01 weightpercent, related to said chlorinated hydrocarbon, of a substanceselected from the group consisting of pyrrole and N-methyl pyrrole.

2. A process for inhibiting the deccomposition of a chlorinatedhydrocarbon selected from the group consisting of dichlorethylene,trichlorethylene and perchlorethylene during contact with metals whichcomprises maintaining dissolved therein from 0.001 to 0.02 weightpercent of an amine selected from the group consisting of ethylenediamine, trimethylene diamine and 1.2-propylene diamine, and 0.005 to0.01 weight 5 of a subtsance selected from the group consisting ofpyrrole and N-methyl pyrrole.

References Cited UNITED STATES PATENTS 2,043,257 6/1936 Missbach260-6525 3,189,552 6/1965 Sims 260-6525 2,803,676 8/1957 Willis et a1260-6525 FOREIGN PATENTS 601,666 7/1960 Canada.

LEON ZIVER, Primary Examiner.

M. JACOBS, Assistant Examiner.

US. Cl. X.R. 252-153

